As known, wireless sensor networks are widely employed for acquiring a wide range of environmental and/or ambient information, such as meteorological data, earthquake data, flooding data, pollution levels, or public safety hazards, such as brush fires, bio-chemical accidents, attacks, etc.
An example of a wireless sensor network is provided in WO 2005/119981 teaching a wireless sensor network, employing a peer-to-peer network architecture for controlling and reporting environmental changes.
In the proposed solution, the information acquired by the sensors is gathered in a monitoring station through local transport routers that communicate directly with the sensor network and the monitoring station. The transport routers are reported as power cell towers, radio transmitters, microwave transmitters. It is thus clear that implementing a sensor network also requires establishing a monitoring station relatively close to the transport routers, in any case in the range covered by them. This known system does not disclose how the information acquired by a plurality of sensor networks can be gathered and analyzed by a unique monitoring station.
To enhance the reliability of sensor networks, US Patent Application 2006/013154 teaches a method to redound sent information packets by forwarding them using a directional flooding technique that preserves the entire network from excessive power consumption. The flooding of an information packet, from a source sensor node to one or more destination nodes, is accomplished in the direction that approaches a destination node on the basis of directional information (minimum hop count). It is therefore possible to obviate the transmission of unnecessary packets and consequently to reduce the whole energy consumption.
The taught method, as well as other blind flooding techniques, minimizes the number of hops each packet undergoes before reaching a destination node, but all packets are treated in the same way, irrespective of the information they carry. Each sensor node sends all packets to its neighbor nodes without performing any selection among them. Thus, the taught method is still inefficient in terms of power saving for the nodes involved in the flooding, and can cause node congestion events that may compromise the management of emergency situations. For example, if all packets are treated so as to minimize the number of hops, some sensor nodes could be overloaded, thus considerably increasing the delay time of all packets transiting there. As a consequence, urgent information could reach the destination node with an excessive delay.